$8,000-$9,000 for a generator, 3 rooftop units at $1,000 each and the rest would be costs associated with labor. Vic (http://www.eastcoastcustombus.com/ ) said since the lights run down the center isle and the electrical wiring for them is located in the middle of the bus rooftop, the AC units would have to be located on either side and somewhat “slanted.” He warns that this may not be aesthetically pleasing but does not know of any other way to install them.